Ananka is in danger of being sent to a remote boarding school; Kiki's life (as always) is in danger, Betty seems to have found love in all the wrong places, and Oona….well, Oona's the one in the most serious trouble of all. From Chinatown to Fifth Avenue, whether they are rescuing kidnapped children or resuscitating an ancient Empress at the Metropolitan Museum of Art, the Irregulars have a knack for finding trouble, and putting it out of its misery.

Fourteen-year-olds Ananka Fishbein, Kiki Strike, and the other Irregulars encounter a Chinese mummy, a ghost, trained squirrels, and old enemies as they try to stop an art forgery ring and safeguard the secret streets hidden beneath New York City.